If the perception and judgment of top coaches and former leading players is correct then Britain's Laura Robson, who turned 15 during the first week of the Australian Open, will be emulating Andy ­Murray's rise to the top within three or four years. Some believe it may be sooner.

"She can compete with those girls already," said her Dutch coach, Martijn Bok. "But if you want to do that consistently you need also to get physically and mentally stronger." This year she will train with Gil Reyes, Andre Agassi's former fitness guru, who also helped Spain's Fernando Verdasco reach the men's semi-finals where he lost to the new champion, Rafael Nadal.

Although Robson lost the Australian Open ­junior final by 6–3, 6–1 to Russia's Ksenia ­Pervak, almost three years her senior and ranked just outside the WTA top 150, Bok felt Robson, the Wimbledon junior champion, had made good progress in extremely the conditions. "She was ­focusing on what she needs to do to play good tennis instead of ­thinking of the results. It's what the top players like Roger Federer and Nadal do really well. They play one point at a time, and focus on what they know works for them. They're tough like that.

"The Russian girl played like a wall. She moved unbelievably well and Laura needs to learn how to break that wall down. I thought she was a ­little bit up and down mentally in the final and physically tired, but with the heat it was a very tough, long, draining week and I think she handled it well. She had a great tournament."

Women's tennis is at a low ebb. That Jelena Jankovic became the first woman to finish the year as the world No1 without ever having won a slam showed an inherent weakness at the top, exacerbated by Justine Henin's shock retirement before the French Open and the continuing injury problems of Maria Sharapova, last year's Australian champion.

With Ana Ivanovic, the champion at Roland Garros, ­losing her form thereafter, and none of the other younger players ready to step up the challenge as yet, the moment was ripe for the re-emergence of the Williams sisters.

Venus retained her hold on the Wimbledon title, beating her younger sister, ­leaving Serena to regain her domination of the hard courts by winning first the US title and then the Australian. Of her 10 slams, which places her clear in seventh place overall, all but three (Wimbledon 2002 and 2003, and the French Open 2002) have been on the hard courts of New York and Melbourne. That she is now No1 is fitting. "I always believe I'm the best, whether I'm No1 or whether I'm 100," she said. "You should never be surprised by anything that I do."

Venus, who has won seven slams, will be 29 years old in June, and Serena 28 in September. They have always been careful not to overextend themselves in terms of tournaments, so it is reasonable to suppose they may go on winning grand slam tournaments for a couple more years. "I feel like I can go forever," said Serena. It would mean much for her to equal or pass Billie Jean King's 12 majors, though the 18 of Chris Evert and Martina Navratilova are probably beyond her.

Should she win at Roland Garros, by some distance her least successful slam, then the thought of a calendar slam might act as a considerable spur. She won four majors back to back from the French Open in 2002 through to the 2003 ­Australian Open, her "Serena slam", and is now two away from a repetition. Much may depend on whether Sharapova's shoulder is ­properly mended after last year's operation. As for keeping the No1 spot, it holds no great interest for Williams, principally because she rarely plays enough WTA tournaments to hold on to it. The slams are quite a different matter.